Erm, well, slime. Most of these are taken form Dungeons and Dragons.
Black Pudding -- Green Slime -- Grey Ooze -- Ochre Jelly -- Pudding Princess -- Purple Bavarian -- Red Marshmallow -- Yellow Jelly -- White Mousse
A variety of "deadly pudding" from D&D which produces a corrosive acid that can dissolve metal.
IMAGE: A black pudding from D&D
Originating in D&D, green slime (one of two types of slime, the other being olive slime) is an immobile growth found in caves which grows by turning creatures into more green slime.
IMAGES: An olive slime from D&D
The grey ooze is from D&D. According to the Monstrous Manual, it resembles a rock formation.
IMAGE: A grey ooze from D&D
Jellies are large amoeba-like creatures from D&D. Ochre jelly is the "basic" type (as opposed to the more dangerous mustard jellies and slithering trackers), while yellow jelly appears to be a Square creation, although mustard jelly turns yellowish-brown when attacking.
IMAGES: The slithering tracker, a type of jelly from D&D
After black puddings arrived in FF via D&D, Square seems to have expanded on the idea, resulting in these weirdos.
As far as I can tell, there is no dish called a "Bavarian" - there are, however, several with "Bavarian" in their names - Bavarain rice pudding, Bavarian cream etc, so it's liekly that the purple Bavarian is a reference to one of these. Or maybe the mosnter designer just has some beef against people from Bavaria.
IMAGE: A deadly pudding from D&D
Back to...BLACK PUDDING



GREEN SLIME


GREY OOZE

OCHRE JELLY, YELLOW JELLY


PUDDING PRINCESS, PURPLE BAVARIAN, RED MARSHMALLOW, WHITE MOUSSE

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